Fumigation



Patented Aug. 23, 1938 UNITED STATES FUMIGATION John M. Baer, Chicago,Ill., .assignor to The Guardite Corporation, a corporation of IllinoisNo Drawing. Application February 19, 1937, Serial No. 126,705

6 Claims.

This invention relates to fumigation and more particularly to fumigationof products containing insects, insect larvae and eggs.

As described in Merriam and Wiles Patent N0.

2,080,179, issued May 11, 1937, the boiling of water may be used toclear the interstices of a product of air, and when followed byintroduction of fumigant at higher pressure, permits complete permeationof the product by the fumigant.

1 It has now been discovered that by using this procedure, insects,insect larvae and eggs of insects may be killed with steam attemperatures which heretofore had no appreciable deleterious efiect uponthem. This is particularly valuable 5 in the case of materials such asgrain, fruitsand similar articles where the starch or gluten may bedamaged by higher temperatures, or where enzymes may be destroyed oradversely affected.

As an example of the process, wheat was introduced into a closedcontainer at a temperature of about 79 F. The container was thenevacuated and the evacuation was continued for thirty minutes, at theend of which time the wheat had a temperature of 61 and the absolutepressure was about .32 inch. Steam was then introduced to raise thetemperature of the wheat to 122 F. and the temperature was kept at thispoint by four additions of 'steam for thirty minutes. The pressure inthe container at this point was approximately 3.54 inches.

The wheat,-which originally had a moisture content of 9.2 had been mixedwith enough external surface water to bring its value to 14.2%, andafter the steaming operation had a thoroughly permeated moisture contentof 14.5%.

7 As another example of the process, test barrels of wheat were placedin a vacuum chamber with screened salve boxes containing insects andglass tubes carrying flour beetle eggs buried at a depth 40 of eighteeninches in the middle of the barrels. Other boxes and tubes were placedon the surface of the grain. The vacuum pumps (steam ejectors) werestarted and run for sixty minutes. At the end of thirty minutes anabsolute pressure of .20 inch was obtained, and at the end of an hourthe 1 .45 absolutepressure was .15 inch. At that time, the

temperature of the grain had been reduced from 5 F. to 53 F.

Steam was then introduced to raise the temperature into the requiredrange of to 130 F. and maintain it at that point a sufiicient period todestroy the insect infestations.

The time required for killing varies with the a temperature. At 120 F.,following evacuation,

the insects, larvae and eggs are killed almost instantaneously. At F., atime of about five minutes is required and at 100 F. about 20 minutes isrequired. Somewhat lower temperatures than 100 F. may be employed butbelow this temperature the time requirements increase very rapidly. v

Temperatures above F. may be employed where they will not damage thematerial treated, but are not necessary for any ordinary purpose.

This process makes it possible to disinfect articles with steam at acost far below any disinfecting operation heretofore possible. The costof the steam is negligible and no other fumigating gas is required.

This application is a continuation-in-part of 15 my co-pendingapplication, Serial No. 110,405, filed November 11, 1936.

I claim:

1. The method of. accelerating the fumigation of an insect-infestedproduct in bulk, which consists essentially of removing substantiallyall noncondensible gas from the product and then treating theinsect-infested product with steam to produce a temperature of not morethan approximately 100 to F. and maintaining the temperature at thisrange from approximately 20 to 0 minutes, the higher temperaturecorresponding to the lower time, whereby the product is substantiallyfreed from insect infestations.

2. The method as set forth in claim 1 in which 30 the product is freedfrom non-condensible gas by subjection to a high enough vacuum to causeboiling of contained moisture at the prevailing temperature andcontinuing the boiling-and evacuation until substantially allcondensible gas has been washed out by the water vapor.

3. The method as set forth in claim 1 in which the product is a fruit.

4. The method as set forth in claim 1 in which the product is a grain.40 5. The method as set forth in claim 1 in which the product is astarchy product.

6. The method of accelerating the fumigation of an insect-infestedproduct in bulk, which consists essentially of removing substantiallyall noncondensible gas from the product and then treating theinsect-infested product with steam to produce a temperature ofapproximately 100 F., and maintaining the temperature at this range forapproximately 20 minutes, whereby the product is 50 substantially freedfrom insect infestations.

JOHN M. BAER.

